Metros!
Got at b3co.com!
Now, my total ought to be higher, because the following are missing: the Bonn/Cologne Stadtbahn (which might count twice), Bonn's local streetcar system, the Zeebrugge coastal streetcar, the Potsdam streetcar, the Graz Strasse/Stadtbahn, and possibly the London Docklands Light Railway (which, I would argue, should be treated as a separate entity).